The present invention relates to sterilization of wastes, primarily to sterilization of medical wastes, e.g. bandages, needles, disposable syringes, gloves, test tubes, blades etc.
More particularly the invention concerns sterilization treatment of wastes within a sealed container with the aim of microwave energy, produced by a magnetron source.
It should be emphasized however, that the present invention is not limited strictly to the sterilization of medical wastes and it can be successfully employed in many other applications as well, in which sterilization treatment of wastes is required.
Environmentally safe disposing of wastes is expensive measure, since relatively economical means like refusing, polygonal burial, incineration is either forbidden or are insufficiently safe.
Therefore numerous devices for disinfection medical wastes have been devised for treatment of medical wastes locally. These devices employ various sources of energy for treatment and the further description will be referred to those sterilization devices, which are provided with autonomous sources of microwave energy.
Among these dedicated devices one can mention, for example, device for heating of articles and organisms, as described in U.S. Pat. No. 5,098,665. This device contains microwave emission device, consisting of a plurality of magnetrons emitting microwave radiation into a sterilization chamber. The magnetrons are configured to enable the output density be uniformly distributed over the interior of the sterilization chamber, thus enabling the infected material to be uniformly and completely sterilized.
The other known microwave sterilization apparatus is disclosed in U.S. Pat. No. 5,246,674. This apparatus includes an injection unit by which water or other liquid is introduced into the material to be treated depending on the water content of the material.
Still further apparatus for controlled microwave heating apparatus is described in U.S. Pat. No. 5,320,804. The apparatus comprises a microwave chamber with a turntable that is capable to oscillate and rotate, a source of microwave radiation and pressure responsive controller, capable to control the source of microwave radiation.
In U.S. Pat. No. 3,222,603 is disclosed an apparatus in which infectious medical wastes are treated by microwaves during an initial stage and then by hot air supplied to treatment chamber and circulating therein.
The main disadvantage of the known in the art sterilization devices is associated with the fact, that they require excessive treatment time for completing the process. The reason for this lies in the electro physical construction of the wave-guides, employed in these devices. The known in the art microwave sterilization apparatuses employ wave-guides defined by opened configuration, extending in one direction towards the treatment chamber. In accordance with the present invention it has been empirically revealed, that this configuration is not the most efficient one and microwave energy can be utilized more efficiently, when the wave-guide has closed configuration, in which the waves can propagate from two opposite directions towards each other and collide in a common point, located within the sterilization area. It has been found, that the collision is accompanied by producing of pick of energy, which is released with the microwaves and therefore this configuration of the wave-guide renders the whole process more efficient and economical, since the time, required for the sterilization treatment sufficiently shortens.
The further disadvantage of the known sterilization devices is their relatively large size and complexity, and therefore inconveniency for use in small clinics and other medical institutions.
Still further disadvantage of the prior art sterilization devices lies in the fact, that they usually don""t recycle the hot air releasing from the treatment chamber. As a rule this air exits directly into atmosphere and since the exhausted air has been in direct contact with the wastes it pollutes the environment.
Therefore despite the fact that different sterilization devices for treatment of medical wastes have been devised there still exists a need for a new and improved device, which is compact, simple, inexpensive and efficient.
The object of the present invention is to provide a new and improved microwave sterilization apparatus, which sufficiently reduce or overcome the above-mentioned drawbacks of the known in the art sterilization apparatuses.
In particular the main object of the present invention is to provide a new and improved sterilization apparatus, enabling more efficient and fast sterilization.
The further object of the present invention is to provide a new sterilization apparatus, which is inexpensive and which has simple and compact construction.
The third object of the present invention is to provide a new and improved sterilization apparatus, which enables recycling of the air, exiting the apparatus and thus is environmentally friendly.
The above and other objects and advantages of the present invention can be achieved in accordance with the following combination of its essential features, referring to different embodiments thereof.
In accordance with the main embodiment of the invention the apparatus comprises:
a) a hermetically closable treatment chamber, configured as microwave-transparent, pressure retaining vessel, in which said medical wastes are received and undergo the sterilization process,
b) a source of microwave energy, substantially a magnetron with a wave-guide for directing the microwaves, emanated by said source to the interior of the treatment chamber,
c) an electrical power supply means operatively coupled with the magnetron, said power supply means is responsible for establishing and maintaining of microwave radiation, emanating from the magnetron,
d) an appropriate control and instrumentation means for monitoring the electrical parameters of said power supply means,
e) a liquid medium reservoir, which is in fluid communication with the interior of the treatment chamber to supply the liquid medium to the interior of the treatment chamber to produce steam upon exposure the said liquid medium to the microwave energy,
f) a steam release means, which is in fluid communication with the interior of the treatment chamber, said steam release means is adapted to control pressure within the chamber during the sterilization process,
wherein said wave-guide comprises a hollow duct communicating with the interior of the treatment chamber, said duct is configured as closed path directing the microwaves produced by the magnetron first in two opposite directions and then in two approaching directions to enable their collision in a meeting point within the treatment chamber.
In a further embodiment the wave-guide is configured as a body, defined by a mirror symmetry and by a plane of symmetry, wherein said treatment chamber is located with respect to the wave-guide in such a manner, that its plane of symmetry lies in the treatment chamber.
In the third embodiment the said treatment chamber comprises an outer tubular shell, which is receivable within the wave-guide, said shell is provided with at least two opposite through-going windows to enable passing the microwaves therethrough, said shell is lined by a microwave transparent lining.
In accordance with the other embodiment the apparatus is provided with a collection bin for collecting the sterilized wastes.
In a still further embodiment the treatment chamber is located above the collection bin and is provided with an input door for opening the chamber and loading the wastes thereinto and with an output door for unloading the sterilized wastes therefrom.
As per another embodiment the input door and the output door is operated by a dedicated opening and closing mechanism, said mechanism is capable to close the respective door and to seal the treatment chamber tightly.
In an additional embodiment the tubular shell is configured substantially as a cylinder having its longitudinal axis located preferably within the plane of symmetry of the wave-guide.
According to yet another embodiment the tubular shell is made as an integral part of the wave-guide.
In still further embodiment, referring to a method for sterilization of wastes by exposing them to microwave energy it comprises the following sequence of steps:
g) Placing said wastes within a treatment chamber, configured as microwave-transparent, pressure retaining vessel
h) Generating of microwaves, substantially by a magnetron source
i) Directing said microwaves through a hollow wave-guide from the magnetron source to the interior of the chamber
j) Exposing the wastes placed within the chamber to the microwave energy.
wherein said microwaves are supplied to the interior of the treatment chamber from two opposite directions to cause their collision within the chamber.
In the further embodiment the step of directing of the microwaves is carried out along a closed path first in two opposite directions and then in two approaching directions to bring the microwaves approaching the chamber from two opposite sides to collision within the treatment chamber.
The present invention in its various embodiments has only been summarized briefly. For better understanding of the present invention as well of its advantages, reference will now be made to the following description of its embodiments with reference to the accompanying drawings.